Aligner having shared rotation shaft

ABSTRACT

An illumination optical system is revolved at a given speed around a rotation shaft and emanates exposure light onto a reticle. The light having passed through the reticle is projected onto a semiconductor substrate, by means of a projection optical system which is revolved around the rotation shaft such that a relative positional relationship between the illumination optical system and the projection optical system is maintained.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a semiconductor manufacturing system,and more particularly, to an aligner for transferring a minute pattern,such as a semiconductor integrated circuit pattern.

2. Description of the Background Art

A scan stepper has hitherto been employed as an aligner at the time offorming a minute pattern such as a semiconductor integrated circuit,during semiconductor manufacturing processes.

A conventional aligner will be now described.

FIG. 5 is a conceptual view for describing a conventional aligner, andFIG. 6 is a conceptual view for describing exposing operation performedwith the conventional aligner.

As shown in FIG. 5, reference numeral 101 designates an illuminationoptical system: 102 designates a reticle serving as an original transferplate; 103 designates a projection optical system; and 104 designates asemiconductor substrate serving as a substrate on which a pattern is tobe transferred.

In the aligner shown in FIG. 5, the illumination optical system 101 andthe projection optical system 103 are fixed. While exposing operation isperformed, the reticle 102 and the semiconductor substrate 104 are movedin synchronism with each other.

In more detail, as shown in FIG. 6, the reticle 102 and thesemiconductor substrate 104 are moved over a slit-shaped exposing region110, whereby a pattern 120 of the reticle 102 corresponding to theexposing region 110 is transferred onto the semiconductor substrate 104.

By means of moving the reticle 102 and the semiconductor substrate 104,the pattern 120 of the reticle 102, which extends beyond the exposingregion 110, is transferred onto the semiconductor substrate 104.

However, in the above conventional aligner, a pattern 120 is exposedonto the semiconductor substrate 4 by means of moving the reticle 102and the semiconductor substrate 104 in a synchronous manner in onedirection. During a period between a single exposing operation forsingle shot (i.e., a single scanning operation) and the next exposingoperation, the reticle 102 and the semiconductor substrate 104 are movedin the reverse direction.

For this reason, the conventional aligner must accelerate and deceleratethe reticle 102 and the semiconductor substrate 104 for every scanningoperation. Therefore, great stress is generated in the aligner.

The accuracy of pattern transfer is deteriorated by distortion orvibration ascribable to the stress.

SUMMARY OF THE INVENTION

The present invention has been conceived to solve thepreviously-mentioned problems and a general object of the presentinvention is to provide a novel and useful aligner for forming asemiconductor substrate by means of exposing, and is to provide a noveland useful method of manufacturing a semiconductor device using analigner.

A more specific object of the present invention is to provide an alignerthat forms a pattern on a semiconductor substrate with high accuracy.

A more specific another object of the present invention is to form apattern on a semiconductor substrate with high accuracy by use of analigner.

The above objects of the present invention are attained by a followingaligner for forming a pattern on a semiconductor substrate by means ofexposing, and by a following method of manufacturing a semiconductordevice using an aligner.

According to one aspect of the present invention, aligner for forming apattern on a semiconductor substrate by means of exposing comprises arotation shaft; an illumination optical system which is revolved aroundthe rotation shaft and emanates exposure light; a reticle through whichthe exposure light originating from the illumination optical system ispassed; and a projection optical system which is revolved around therotation shaft such that a relative positional relationship between theillumination optical system and the projection optical system ismaintained, and the projection optical system projects the light passedthrough the reticle onto the semiconductor substrate.

In the aligner for forming a pattern on a semiconductor substrate bymeans of exposing, while exposing operation is performed, theillumination optical system and the projection optical system arerevolved around the rotation shaft.

Therefore, there is obviated a necessity of moving the reticle back andforth for a single shot of exposing, which would otherwise be requiredby the conventional aligner. Thus, generation of stress can be preventedin the aligner, thereby enabling highly-accurate exposing of a pattern.

According to another aspect of the present invention, in a manufacturingmethod of a semiconductor device using aligner, exposure light isemanated onto a reticle from an illumination optical system, and theillumination optical system revolving around a rotation shaft in anemanation step. Next, the light passed through the reticle is projectedonto a semiconductor substrate by way of a projection optical system,and the projection optical system revolving around the rotation shaftsuch that a relative positional relationship between the illuminationoptical system and the projection optical system is maintained in aprojection step.

In the method of manufacturing a semiconductor device, generation ofstress can be prevented in the aligner, thereby enabling highly-accurateexposing of a pattern, as well as the above-mentioned aligner.

Other objects and further features of the present invention will beapparent from the following detailed description when read inconjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a conceptual view for describing an aligner, according to afirst embodiment of the present invention;

FIG. 2 is a view for describing the movement of the exposing region onthe reticle during an exposing operation using the aligner according tothe first embodiment;

FIG. 3 is a view for describing exposing of a pattern on a semiconductorsubstrate during an exposing operation using the aligner according tothe first embodiment;

FIG. 4 is a view for describing a semiconductor substrate after finishedexposing operation performed by the aligner according to the firstembodiment;

FIG. 5 is a conceptual view for describing a conventional aligner; and

FIG. 6 is a conceptual view for describing exposing operation performedwith the conventional aligner.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following, principles and embodiments of the present inventionwill be described with reference to the accompanying drawings. Themembers and steps that are common to some of the drawings are given thesame reference numerals and redundant descriptions therefore may beomitted.

First Embodiment

FIG. 1 is a conceptual view for describing an aligner, according to afirst embodiment of the present invention.

As shown in FIG. 1, reference numeral 1 designates an illuminationoptical system; 2 designates a reticle; 21 designates a reticle holder;3 designates a projection optical system; 31 designates a firstreflection mirror; 32 designates a second reflection mirror; and 33designates a projection lens. Moreover, reference numeral 4 designates asemiconductor substrate; 41 designates a stage; 5 designates asupport/rotation mechanism; 51 designates a rotation shaft; 52designates a rotary plate; and 53 designates a support plate.

The illumination optical system 1 emanates exposure light onto thereticle 2. The illumination optical system 1 is disposed on the rotaryplate 52, and the system 1 is revolved around the rotation shaft 51 inconjunction with rotation of the rotary plate 52.

The reticle 2 is an original transfer plate having a pattern drawnthereon. The exposure light emanated from the illumination opticalsystem 1 is passed through the reticle 2. The reticle 2 is held by thereticle holder 21. The reticle 2 and the reticle holder 21 are placed onthe support plate 53, which does not rotate.

The projection optical system 3 is disposed on a rotary plate (notshown) of the support/rotation mechanism 5, and the system 3 is revolvedaround the rotation shaft 51 such that the relative positionalrelationship (to be described later) between the projection opticalsystem 3 and the illumination optical system 1 is maintained. Theprojection optical system 3 projects the light passed through thereticle 2 onto the semiconductor substrate 4. More specifically, theprojection optical system 3 transfers an inverted-and-reversed image ofthe pattern of the reticle 2 onto the semiconductor substrate 4.

The projection optical system 3 comprises a first reflection mirror 31,a second reflection mirror 32 and a projection lens 33. The tworeflection mirrors 31 and 32 and the projection lens 33 are disposed onthe rotary plate (not shown), and are revolved around the rotation shaft51 so as to maintain a positional relationship to be described later;i.e., a relative positional relationship among the reflection mirrors 31and 32, the projection lens 33 and the illumination optical system 1.

The first reflection mirror 31 is disposed such that a reflectionsurface 31 a is spaced distance R2 away from the axis of the rotationshaft 51. The second reflection mirror 32 is disposed such that areflection surface 32 a is spaced distance R1 away from the axis of therotation shaft 51. The projection lens 33 is interposed between thesecond reflection mirror 32 and the semiconductor substrate 4.

Here, “R1” is the distance from the reflection surface 32 a to the axisof the rotation shaft 51 (i.e., a distance from an optical axis B to beprojected on the semiconductor substrate 4 to the axis of the rotationshaft 51), and “R2” is the distance from the reflection surface 31 a tothe axis of the rotation shaft 51 (i.e., a distance from an optical axisA passing through the reticle 2 to the axis of the rotation shaft 51).Further, a ratio of R2 to R1 (R2/R1) accurately matches a scale-downfactor.

Hence, geometrical similarity equal to the scale-down factor (R2/R1)exists between the movement of an exposing region 20 on the reticle 2relative to the rotation shaft 51 and the movement of an exposing regionon the semiconductor substrate 4 relative to the rotation shaft 51.

The first reflection mirror 31 reflects the light passed through thereticle 2 in a horizontal direction. The second reflection mirror 32reflects the light reflected from the first reflection mirror 31 in thedirection perpendicular to the surface of the semiconductor substrate 4;that is, toward the projection lens 33. The projection lens 33 projectsthe light reflected from the second reflection mirror 32 onto thesemiconductor substrate 4 in a scaled-down manner.

The semiconductor substrate 4 is a wafer coated with, for example, aphotosensitive agent (photoresist). The semiconductor substrate 4 isheld by the stage 41, which does not rotate. After having been exposedto a single shot of pattern, the semiconductor substrate 4 is moved in astepwise manner by means of the stage 41 (Stepping movement shown inFIG. 3).

The support/rotation mechanism 5 comprises the rotation shaft 51, therotary plate 52 and the support plate 53. Further, the support/rotationmechanism 5 comprises a rotary plate (not shown) which rotates aroundthe rotation shaft 51. The projection optical system 3 is disposed onthe rotary plate.

The illumination optical system 1 is disposed on the primary surface ofthe rotary plate 52, and the rotary plate 52 rotates around the rotationshaft 51.

The support plate 53 is for holding the reticle holder 21, and thesupport plate 53 is fixed, i.e. not rotate.

The illumination optical system 1 and the projection optical system 3are revolved at a given speed by means of the respective rotary platesof the support/rotation mechanism 5. Preferably, the speed is set withinthe range of 0.5 to 3.0 m/sec. The reason for this is that, if the speedassumes a value of under 0.5 m/sec., throughput becomes insufficient. Incontrast, if the speed exceeds 3.0 m/sec., fixation of the projectionlens 33 becomes difficult.

The above-described aligner can be summarized as follows: theillumination optical system 1 emanates exposure light while revolvingaround the rotation shaft 51. The reticle 2 pass through the exposurelight originating from the illumination optical system 1. The projectionoptical system 3 is revolved around the rotation shaft 51 such that therelative positional relationship between the illumination optical system1 and the projection optical system 3, and the projection optical system3 projects the light passed through the reticle 2 onto the semiconductorsubstrate 4.

Next, with reference to FIGS. 1 to 4, the exposing method using thealigner according to the present embodiment will now be described.

FIG. 2 is a view for describing the movement of the exposing region onthe reticle during an exposing operation using the aligner according tothe present embodiment. FIG. 3 is a view for describing exposing of apattern on a semiconductor substrate during an exposing operation usingthe aligner according to the present embodiment. FIG. 4 is a view fordescribing a semiconductor substrate after finished exposing operationperformed by the aligner according to the present embodiment.

As shown in FIG. 1, the illumination optical system 1 is revolved aroundthe rotation shaft 51, and the illumination optical system 1 emanatesexposure light onto the reticle 2. The projection optical system 3 isrevolved around the rotation shaft 51 as well as the illuminationoptical system. Here, the illumination optical system 1 and theprojection optical system 3 are revolved around the rotation shaft 51 inconjunction with each other such that the relative positionalrelationship between the illumination optical system 1 and theprojection optical system 3 (described previously) is maintained. Theillumination optical system 1 and the projection optical system 3 arerevolved at a given speed, wherein the speed is set within a range of0.5 to 3.0 m/sec.

As shown in FIG. 2, when the illumination optical system 1 is revolvedin the manner as mentioned above, the wedge-shaped exposing region(exposing slit) 11 is moved over the pattern 20 of the reticle 2.

Here, an integrated amount of exposure light (illumination light) at anarbitrary point on the pattern 20 of the reticle 2 over which theexposing region 11 has moved becomes uniform.

Next, the light passed through the reticle 2 is projected onto thesemiconductor substrate 4 by means of the projection optical system 3.

More specifically, the light passed through the reticle 2 is reflectedby the first reflection mirror 31 in a horizontal direction, wherein thereflection surface 31 a of the first reflection mirror 31 is spaced onlydistance R2 away from the axis of the rotation shaft 51.

Next, the light reflected from the first reflection mirror 31 isreflected by the second reflection mirror 32 in a perpendiculardirection; that is, toward the projection lens 33, wherein thereflection surface 32 a of the second reflection mirror 32 is spacedonly distance R1 away from the axis of the rotation shaft 51.

Next, the light reflected from the second reflection mirror 32 isprojected onto the semiconductor substrate 4 by way of the projectionlens 33.

As shown in FIG. 3, by means of the above-described exposing operation,the image of the pattern 20 of the reticle 2, which is exposed throughthe exposing region 11, is formed on the semiconductor substrate 4 as aninverted-and-reduced image (40).

Here, as shown in FIG. 1, the illumination optical system 1 and theprojection optical system 3 are disposed such that the ratio of distanceR2 from the optical axis A to the axis of the rotation shaft 51 todistance R1 from the optical axis B to the axis of the rotation shaft51; that is, R2/R1, becomes identical with the scale-down factor bywhich the pattern 20 on the reticle 2 is to be pattern 40 onto thesemiconductor substrate 4 by means of exposing.

Accordingly, a reduced pattern 40 which is symmetrical about the pattern20 on the reticle 2 and converges with respect to a point on therotation shaft 51 is patterned onto the semiconductor substrate 4 bymeans of a single shot of exposing.

After the semiconductor substrate 4 has been moved stepwise in themanner (Stepping movement) as shown in FIG. 3, the above-mentionedexposing operations are repeated.

After all the exposing operations have been completed, a plurality ofpatterns 40 are formed over the entire surface of the semiconductorsubstrate 4, as shown in FIG. 4.

As described above, in the aligner and the exposing method according tothe first embodiment, the illumination optical systems 1 and theprojection optical system 3 are revolved around the rotation shaft 51,and the pattern 20 drawn on the reticle 2 is patterned onto thesemiconductor substrate 4 through exposing.

There is obviated a necessity of moving the reticle 2 back and forthevery exposing of a single shot, which would otherwise be required bythe conventional aligner. Thus, generation of stress can be prevented inthe aligner. Therefore, distortion and vibration of the aligner can beprevented, thereby enabling highly-accurate exposing of a pattern.

The optical systems 1 and 3 are revolved at a given speed, henceexposing operation can be performed stably, thereby enablinghighly-accurate exposing of a pattern. Further, the speed is set to avalue ranging from 0.5 to 3.0 m/sec., thereby improving throughput.

The above-mentioned aligner has a pair of optical systems; that is, oneillumination optical system 1 and one projection optical system 3. Thealigner may be provided with a plurality of sets of optical systems. Inthis case, exposing operation can be performed a plurality of timesduring a single rotation-of the rotation table 52. Therefore, throughputcan be improved to a much greater extent.

Further, a plurality of pairs of optical systems 1 and 3 are disposed atuniform intervals around the rotation shaft 51, thereby improving abalance in weight of the aligner. Accordingly, distortion or vibrationof the aligner can be prevented, thereby enabling a further stableexposing operation. Further, as mentioned above, exposing operation isperformed at a given rotation speed, thereby enablingconsiderably-stable exposing operation. Hence, a pattern can be exposedat high speed and with high accuracy.

The balance in weight of the aligner can be improved, by means ofarranging weights which are equal in weight and center of gravity withthe optical systems 1 and 3, thereby enabling stable exposing of apattern.

The plurality of illumination optical systems 1 which emanate exposurelight of respective different wavelengths, or the plurality projectionoptical system 3 having lenses of respective different numericalapertures (N.A.) may be used. Thus, exposure under a plurality ofexposing conditions can be performed in the aligner.

The aligner according to the present embodiment may be provided with aplurality of reticles 2 and a plurality of semiconductor substrates 4corresponding to the reticles 2. As a result, the plurality ofsemiconductor substrates 4 can be exposed to the light during a singlerotation of the optical systems 1 and 3. Therefore, throughput can beimproved. In addition, if the aligner employs the above-mentionedplurality of sets of optical systems 1 and 3, the throughput can beimproved to much a greater extent.

This invention, when practiced illustratively in the manner describedabove, provides the following major effects:

According to a first aspect of the present invention, generation ofstress in an aligner can be prevented, thereby enabling highly-accurateexposing of a pattern.

In a preferred variation of the present invention, aninverted-and-reduced image of a reticle can be exposed onto asemiconductor substrate with high accuracy by means of exposing.

In a preferred variation of the present invention, an illuminationoptical system and a projection optical system are revolved at a givenspeed, thereby enabling stable exposing of a pattern.

In a preferred variation of the present invention, since the speed isset within the range of 0.5 to 3.0 m/sec., throughput can be improved.

In a preferred variation of the present invention, a balance in weightof the aligner can be improved, and stable exposing of a pattern can beperformed. Further, throughput can be improved.

In a preferred variation of the present invention, a pattern can beexposed under different exposing conditions.

In a preferred variation of the present invention, a pattern can bepatterned onto a plurality of semiconductor substrates by means ofexposing, thereby improving throughput.

Further, the present invention is not limited to these embodiments, butvariations and modifications may be made without departing from thescope of the present invention.

The entire disclosure of Japanese Patent Application No. 2000-379196filed on Dec. 13, 2000 containing specification, claims, drawings andsummary are incorporated herein by reference in its entirety.

What is claimed is:
 1. An aligner for forming a pattern on asemiconductor substrate by means of exposing comprising: a rotationshaft; an illumination optical system which is revolved around saidrotation shaft and emanates exposure light, an optical axis of saidexposure light is different from said rotation shaft; a reticle throughwhich said exposure light originating from said illumination opticalsystem is passed; and a projection optical system which is revolvedaround said rotation shaft such that a relative positional relationshipbetween said illumination optical system and said projection opticalsystem is maintained, and said projection optical system projecting saidlight passed through said reticle onto said semiconductor substrate. 2.The aligner for forming a pattern on a semiconductor substrate by meansof exposing according to claim 1, wherein said projection optical systemincludes a first reflection mirror, a second reflection mirror and aprojection lens, which are disposed such that a relative positionalrelationship to said illumination optical system is maintained; saidfirst reflection mirror reflects said light passed through said reticlein a horizontal direction; said second reflection mirror reflects saidlight reflected from said first reflection mirror in a verticaldirection; and said projection lens projects said light reflected fromsaid second reflection mirror onto said semiconductor substrate in ascale-down manner.
 3. The aligner for forming a pattern on asemiconductor substrate by means of exposing according to claim 2,wherein the ratio of a distance from an axis of said rotation shaft to areflection surface of said first reflection mirror to a distance fromsaid axis of said rotation shaft to a reflection surface of said secondreflection mirror is equal to a scale-down factor of said projectionlens.
 4. The aligner for forming a pattern on a semiconductor substrateby means of exposing according to claim 1, wherein said illuminationoptical system and said projection optical system are revolved at agiven speed.
 5. The aligner for forming a pattern on a semiconductorsubstrate by means of exposing according to claim 4, wherein saidillumination optical system and said projection optical system arerevolved at a speed of 0.5 to 3.0 m/sec.
 6. The aligner for forming apattern on a semiconductor substrate by means of exposing according toclaim 1, wherein a plurality of illumination optical systems areprovided around said rotation shaft at uniform intervals, and aplurality of projection optical systems are provided so as to correspondto said respective illumination optical systems.
 7. The aligner forforming a pattern on a semiconductor substrate by means of exposingaccording to claim 6, wherein said plurality of illumination opticalsystems include illumination optical systems which emanate exposurelight of different wavelengths.
 8. The aligner for forming a pattern ona semiconductor substrate by means of exposing according to claim 6,wherein said plurality of projection optical systems include projectionoptical systems having lenses of different numerical apertures.
 9. Thealigner for forming a pattern on a semiconductor substrate by means ofexposing according to claim 1, wherein a plurality of reticles areprovided around said rotation shaft, and a plurality of semiconductorsubstrates are provided around said rotation shaft so as to correspondto said respective reticles.